


A Mysteriously Good Time

by MadamKuro



Category: Gravity Falls
Genre: 69 (Sex Position), Anal Sex, Blow Jobs, Come Swallowing, Creampie, Cunnilingus, Deepthroating, Developing Relationship, Doggy Style, Drinking Piss, F/M, First Kiss, First Time, First Time Blow Jobs, Fluff and Smut, Hair-pulling, Harems, Impregnation, Loss of Virginity, Main pairing is Pinecest but Dipper also has three other girlfriends too, Marriage Proposal, Mildly Dubious Consent, Mind Control, Multi, No Refractory Period, Sexting, Sibling Incest, Teen Pregnancy, Twincest, Uncircumcised Penis, Underage Kissing, Underage Sex, Unsafe Sex, Vaginal Sex, Watersports, pinecest - Freeform
Language: English
Status: Completed
Published: 2019-12-20
Updated: 2019-12-20
Packaged: 2021-02-26 03:41:16
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 12,385
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21866899
Author URL: https://archiveofourown.org/users/MadamKuro/pseuds/MadamKuro
Summary: Mabel and Dipper love each other more than normal siblings should. Mabel is desperate to be with her brother, but Dipper refuses to act on his feelings. When the duo arrive in Gravity Falls Mabel is determined to seduce her brother while Dipper is determined to get his mind off his feelings for Mabel by successfully wooing Wendy, Pacifica, and Candy. Yet, despite having three needy girlfriends, Dipper can't stop himself from imagining what it would be like to be with his sister instead. In an attempt to spend some quality time with Mabel, Dipper reveals a new entry in the journal that he wants to investigate. The entry describes a mysterious stone and conveys a simple warning: "stay away." After finding the strange stone, Dipper and Mabel are overcome with an unshakable urge to finally have their way with one another. It is impossible to resist...
Relationships: Candy Chiu/Dipper Pines, Dipper Pines/Mabel Pines, Pacifica Northwest/Dipper Pines, Wendy Corduroy/Dipper Pines
Comments: 13
Kudos: 88





	A Mysteriously Good Time

**Author's Note:**

  * For [Corey21](https://archiveofourown.org/users/Corey21/gifts).



> Welcome one and all to MadamKuro's latest and greatest fic! This fic is yet another wish from Corey21 who decided to commission a Pinecest story this time around with a hint of a few other Dipper-centric pairings. A pinch of mystery, a dash of incest, and a whole lot of sex can be found within this wish, so proceed with caution! You wouldn't want the stone to have its wicked way with you either...
> 
> Big thank you to Corey21 for continuing to support my work!

“Are we going on an adventure today or what, Dipper?” Mabel loudly complained as they stood outside the Mystery Shack. 

“Yeah, yeah, just one second, Mabel,” Dipper murmured lowly as he flipped through the pages of the strange yet surprisingly helpful journal he had found a few weeks back. When the summer first began Dipper had been sure that it was going to be an absolute bore staying with Grunkle Stan, but after finding this cryptic journal and discovering that not everything was as it seemed in Gravity Falls, Dipper had been far more inclined to stick around. Every day the journal revealed new secrets and insights into the weird history of the town to them, and every day they were able to vanquish yet another evil presence from the area. It was a righteous and incredibly fun endeavor that the Pines twins had set out on, and today was no different. 

“It was in here somewhere….” Dipper continued searching through the journal for the strange entry that he had stumbled across the other day. 

Mabel sighed exasperatedly before plopping herself down onto a nearby boulder; she knew this was going to take a while. Picking up a stick, she began to entertain herself by drawing little doodles in the sand. 

Muttering to himself and hurriedly flipping through more pages, Dipper’s eyes finally widened when he found the entry he had been searching for. “Aha!” He reread the short scratchy blurb, the handwriting itself seeming to tremble underneath the sketch on the page. 

**_STAY AWAY!!!_ **

Normally, the journal entries would be a tad more intricate the one he was reading. Sure, the entries were typically vague and hard to decipher, but they at least offered more description than this one. The message was so straightforward that Dipper couldn’t help but become intrigued by it, wanting to know what dangers awaited them at the sight mentioned. They had already dealt with gnomes, ghosts, and little psychics, so Dipper believed they were more than capable of handling whatever oddity this entry was warning them about. He re-examined the sketch above the writing. It was a weirdly shaped rock that looked like it belonged in Stonehenge. It seemed enormous so much so that Dipper felt like he would be able to walk right under it once they arrived at it. He had caught a glimpse of the rock previously when he had been running through the forest with the Manotaurs, but at the time, he hadn’t been able to investigate it. Since nothing strange had happened to them recently, Dipper had recruited Mabel to help him uncover the mystery behind the stone. 

“Alright, Mabel, let’s go. I remember the rock was close to the eastern path.”

Finishing off her tiny doodle of Waddles, Mabel beamed and then tossed the stick she had been drawing with. She jumped to her feet with a triumphant cry, more than ready to start their adventure. 

“This is going to be so much fun, Dipper! We haven’t had some quality twin-bonding time in a while.” She smiled to herself. Between all of the crazy encounters they had been having and Dipper’s insatiable thirst for almost any girl that passed him by, the twins hadn’t had much alone time recently, which was odd for Mabel as the two of them were practically inseparable. Even at night when they were alone in their shared room, her brother seemed distant and constantly texting girls. He didn’t seem as interested in Mabel as he had been before, and while she knew that Dipper was starting to hit puberty, she hadn’t expected such a dramatic change in her twin. She missed Dipper...in more ways than one. 

Truth be told, Mabel harbored more than  _ familial  _ love for Dipper. Ever since they were little, she had longed to be with him. He was her knight in shining armour, but she still vividly remembered the day she had confessed to him and the day he had rejected her. The twins had shared a rather passionate romantic kiss, becoming each other’s  _ first  _ kiss, and while Mabel had been more than ready to give herself to her brother then and there, he had put a stop to it. 

_ "Mabel, I'm sorry, but you know that we can't be together. As much as I want to...We just can't."  _

She felt like her heart had been broken that day, though she never did give up her perusal of her brother even now when he had a small harem of other girls to satisfy his desires. 

And just as the two of them were about to set out on their adventure, Dipper’s phone let out a trilling ring that Mabel had grown to despise. 

“One second, Mabel. It’s Wendy.”

She huffed as her brother began to text. She didn’t mind that Dipper now had three girlfriends: Wendy, Pacifica, and Candy. She recalled when they first arrived at Gravity Falls and what Dipper had told her after he met Wendy for the first time. 

_ “I’m going to try and woo that Wendy girl this summer...I think you should find a boyfriend for yourself, Mabel.”  _

_ “Okay little brother, but it won’t change anything. You can fuck Wendy all summer long until she bears your child, yet it won’t change the fact that every time you’re with her, you’ll wish she was  _ me.  _ And, no guy could ever really receive any true romantic affection from me because he won’t be  _ you.  _ So, go ahead and fuck Wendy. It shouldn’t take you more than a week to get into her pants considering what you’re packing  _ downstairs.” 

_ And, Mabel had been right. She had walked in on Dipper fucking Wendy the very next day.  _

She wouldn’t mind  _ sharing  _ Dipper and possibly playing around with the other girls from time to time, but Dipper just wouldn’t allow it. She couldn’t stop butterflies from fluttering in her stomach whenever Dipper was texting or spending time with his girlfriends. When she arrived in Gravity Falls and vowed to have an epic summer romance she hadn’t been joking. She had told herself that while they were away from their parents and friends back home that she would finally attempt to seduce Dipper and get him to release all of his inhibitions. 

While Mabel contemplated her love for her brother, Dipper struggled to contain his flush and the throbbing of his cock as Wendy had sent him a rather provocative photo. 

**_Missing u… :(_ **

Her message was emphasized by a photo in which she was pouting. She was stripped down to the matching lacy pink bra and panties that she knew drove Dipper wild, and her hand was cupping her puffy mound, no doubt stimulating her clothed clit. 

Dipper licked his lips, though at the moment, his cock was craving someone else. He backed out of the chat he had with Wendy to peruse the rest of his messages. He had similar messages from Pacifica and Candy, but he didn’t feel like playing around with them either. His blush darkened as he realized what he wanted: the forbidden fruit itself, Mabel. Ever since he could remember, he had wanted to be with his sister, though he knew they couldn’t ever  _ actually  _ be together since incest was taboo (even in a place as strange as Gravity Falls). In fact, he had developed his little harem here in Gravity Falls simply to distract himself from his increasingly lewd thoughts of Mabel, yet no matter how many times he fucked his girlfriends here, he couldn’t get Mabel off his mind just as she had predicted at the start of the summer. Perhaps he couldn’t fuck her, but...

Deciding he wanted to at least spend some quality time with his sister as she had suggested, he went to text Wendy back. 

**_Sorry babe. Can’t sext right now. I’m with family. I’ll call you tonight._ **

“And,” Dipper drawled as he typed out the last word of his message, “Sent.” He placed his phone back into his pocket, determined not to pull it out again while he was with Mabel. He looked back over his shoulder at her, raising the journal so that she could see the sketch of the rock. “Let’s go find this stone!”

Mabel’s heart skipped a beat at the tender expression Dipper sent her way, and then she was off, following him past the tree line. 

* * *

“It’s weird and it’s a rock…”   
  


“Yep, it would appear so…” 

It hadn’t taken the twins long to stumble across the strange boulder; Dipper’s memory had served him well. They were now standing before the enormous stone that towered over top of their heads. As Dipper had predicted, it was tall enough for him to walk under, which he had done numerous times and yet...He pulled out the journal again to make sure he had read the correct entry. 

**_STAY AWAY!!!_ **

But, what were they supposed to be staying away from? They had already been investigating the stone for at least ten minutes now and absolutely nothing had happened. Other than its size and shape, the stone was pretty normal. There was no weird electromagnetic field surrounding it nor strange creatures guarding it. The two of them had felt completely fine the entire time they had stood in its presence. Something just wasn’t adding up…

“Maybe it’s made out of something strange?” Dipper hypothesized as he once more approached the boulder. He stood underneath it and began to pick at the side of it with his nail in an attempt to scratch a flake of it off that he could properly examine later. 

Mabel was stumped as to how this stone was special. To her, it was like any ordinary rock. She stood right next to it and leaned back on the stone. So much for an exciting adventure...She sighed softly as her eyes trailed back over to her brother. A tender expression morphed her features as she regarded him with true love. He looked like such a dork trying to pick at the rock, but he was  _ her  _ dork, and that would never change even if Dipper had twenty girlfriends. Continuing to fawn over her brother, Mabel suddenly noticed a slight ringing in her ears. She blinked, then focused on the sound. It seemed to be coming from...the rock? Was something finally happening? She stared up at the top of it, waiting for the sky to darken or the rocks to begin crumbling, but once again nothing happened. However, her heart began to beat rapidly inside her chest and heat blossomed across her face because of it. Her mouth felt very dry as if she was completely dehydrated all of a sudden. She let out a loud pant that caught Dipper’s attention. 

He turned from the stone, the journal still open in his free hand, to look at her. He raised a brow. “Mabel? You okay?”

She honed in on the sound of his voice, his baritone turning her brain to mush. One of her hands came up to clutch at her chest; she felt like she was having a heart attack. Her body was growing far too hot, and she noticed that she was feeling warm  _ down  _ there too. This usually only happened when she thought about Dipper in a certain way late at night when she was positive he was asleep...But now, she couldn’t stop the vulgar thoughts that were flashing through her mind. Dipper having his way with her in so many different compromising positions, taking her however he pleased in order to stake his claim on her. Her eyes were hazy as fantasy blended with reality. A small whimper escaped her and then her feet were moving all on their own towards the object of her affections. 

“Mabel?  _ Mabel, are you alright?! _ ” Dipper tried again, growing more and more panicked when Mabel refused to answer him. She started to approach him at a sluggish pace and her eyes appeared blank. Had the stone turned her into a zombie?! “Don’t worry, Mabel. I-I’ll fix this,” he declared, dropping the journal to dash over to his sister. 

He went to place his hands on her shoulders to steady her, though he found that she was just as eager to grab ahold of him. Her hands flew out towards him, clutching onto his shirt with a tight grip. He gulped, his pupils blown as he took in this almost angelic view of his sister. He had always admired her from afar, wishing to be with her and worship every inch of her, but he hadn’t been this close to her in quite some time...Like Mabel, Dipper soon heard the quiet ringing in his ears as well, yet he was far too immersed in his love for his twin to notice. His heart began pounding against his ribcage almost as if it was demanding to be let out and offer itself to Mabel. His hands felt clammy as he gripped her shoulders, and his throat suddenly had a lump in it that he could not dispel. Oddly enough, he even felt his cock twitch inside his pants, a tiny bit of heat beginning to coil in his belly. 

“Dipper...I…,” Mabel whispered, her eyes staring directly at Dipper’s lips. Dipper stupidly waited for her to finish her thought, his eyes blinking ever so slowly as if to not miss a single second of his sister. Subconsciously, he began to pucker his lips, and Mabel’s tongue slipped out of her own mouth to lick hers. There was an intense heat radiating between them that was almost magnetizing. They felt drawn towards each other as all their inhibitions slowly began to fade away. Dipper traced the soft curve of Mabel’s face with his eyes while Mabel gently felt up Dipper’s chest beneath his shirt. 

Unbeknownst to either of them, the stone behind them trembled before emitting a high-pitched buzzing noise around the area. The sound replaced the ringing in their ears, and it slowly drifted off until it was no more. 

A moment passed. A small beat of silence and then…

They were both on each other. Something primal and carnal had overcome them, demanding that they be together this very instant. It was as if a fire had been ignited in them that only burned for the other. Mabel pulled Dipper towards her by his shirt, and Dipper brought Mabel closer by tugging on her shoulders. They met in the middle, connecting their lips for the first time in  _ years _ . A shaky but loud moan tumbled past Mabel’s lips when they met; she hadn’t felt this hot and bothered for her brother in so long. This kiss was much sloppier than their first one had been since they were both incredibly desperate for the other. Their noses collided at first, but Mabel was quick to tilt her head and press even deeper into the kiss. Dipper’s eyes immediately fell shut when his sister’s soft lips descended upon his own. His fingers dug into her shoulders in order to keep himself steady and up on his feet. Why had he shied away from this? Mabel felt positively  _ divine _ , far better than any of his little girlfriends. He had been missing out on so much by not being with her; he would just have to make up for lost time here and now.

Neither of them were completely certain what had come over them. Yes, they had both harbored feelings for the other for quite some time, but they had always been able to control their urges. But at this moment, they both felt like they would  _ explode  _ if they didn’t touch the other like they were truly connected to each other, one in the same. Any thoughts of this being taboo or wrong flew out of their minds. All they were concerned with at the moment was getting each other’s clothes off as fast as possible and then proceeding to make love, something they had always wanted to do but never had the guts to admit. 

As always, Mabel was the first one to make a move. When it came to her love for Dipper she was bold and certain; she knew exactly what she wanted. She puckered her own lips around Dipper’s, squishing them with her own, and her hands slowly danced their way up Dipper’s sides. The tips of her fingers tickled him even through his shirt. A low moan escaped him, but with nowhere else to go, it became trapped in between them. Mabel shamelessly rubbed her thighs together before her hands drifted back down to fiddle with the hem of Dipper’s shirt. Experimentally, Dipper opened his mouth and allowed his tongue to slip out. He lovingly laved at Mabel’s own lips and got a taste of her sweet cherry chapstick; it tasted like everything he wasn’t allowed to want. Mabel’s fingers hooked onto the hem of his shirt and she pulled it up in order to free him of its oppressive heat. He knew it was coming and yet he dreaded having to pull apart from his sister after finally being able to kiss her again. 

With a light smack, he pulled away, though he kept their faces close, close enough so that their hot breaths could intermingle. He only removed one hand from Mabel’s shoulder while the other tightened its grip on her. He used his free hand to take off his cap, flinging it to the side without hesitation. The two of them kicked their shoes off at the same time and used their heels to push off their socks. Mabel let out a bubbly giggle as she went to raise Dipper’s shirt. When it was around his neck he finally released her other shoulder and let her pull his shirt up and over his head. It too was discarded with his cap. Once his skin was bared to the world, he shuddered. He almost felt like he was running a fever, and a layer of sweat had begun to form on his chest and stomach. But, Mabel didn’t seem to mind in the slightest as her own mouth fell open into a tiny “o”. Sure, she had seen her brother shirtless many times, yet there was something about  _ this  _ moment that made her tingle. Her eyes trailed down the entirety of Dipper’s abdomen from the cords of his neck to the blossoming of abs over his stomach, and her clit pulsed to life. 

She couldn’t resist him any longer. All her previously hidden and repressed desires were being amplified in her brain, images of everything that she wanted Dipper to do to her still flashing before her vision. She had never wanted him as badly as she did now...She stepped forward drunkenly to close the small distance between them and ended up falling forward. She splayed her hands out and managed to catch herself on Dipper, her palms resting over his pecs. Her breath caught in her throat as she touched his heated tan skin. She bit down on her bottom lip and went to cup his pecs, squeezing lightly and moaning shakily at how firm they were becoming; Dipper would be a man in no time at all. 

An animalistic growl built up in Dipper’s chest as Mabel fawned over him. Eventually, it tumbled out and then his own hands were shooting forward to grab at the hem of Mabel’s sweater. “My turn,” he practically purred into her ear, and Mabel gasped cutely when her sweater was instantly pulled up and over her head. Dipper flung it backwards, and his pupils dilated when he caught sight of the plain purple bra that was keeping his sister’s breasts covered from him. 

Mabel blushed from her cheeks to her chest, a light rosy hue creeping down her neck. It had been a while since Dipper had seen her without a shirt or bra. As soon as Mabel had started developing breasts, their mother had insisted on her at least wearing sports bras, and now she had officially graduated to a B cup at the start of the summer. Dipper had seen her in bikinis before, but this was different.  _ Fundamentally so _ . Once he removed her bra, it was all over. There would be no going back. 

Dipper realized this himself and gulped, but he was prepared now. It had become increasingly clear to him that no one would replace Mabel in his mind. Just as she had said, he could fuck Wendy, Pacifica, and Candy as many times as he liked, but it wouldn’t change a damn thing. He needed his twin now more than ever, and he was prepared to deflower her with overwhelming care and love. This had always been his destiny, and it was time that he stopped running from it. The ringing in his ears grew dull when he reached his arms out towards her. 

Mabel’s breath caught in the back of her throat as Dipper’s hands snaked around her back and began searching for the clasps of her bra. She pushed herself closer to her brother, burying her face into his neck, in order to inhale his fresh earthy musk. He smelled like newly-dug up soil and roses just like the ones their mother had planted in their backyard when they were younger. Dipper was an expert of undoing bras now after spending so much time with his girlfriends and Mabel’s was easy to maneuver. It took him a simple flick of his wrist to undo the clasps, and he felt her bra slip down against his chest. He took each end of the bra in each hand, then slowly pulled them apart and forward. Mabel lifted her head from him when she felt him moving back. Her blush extended to the tips of her ears, but she refused to shut her eyes; she wanted to witness Dipper’s unhinged reaction to her newly developed breasts. 

At last, Dipper pulled her bra completely off, and it dangled in his hand as his eyes widened to take in the refreshing sight of his braless sister. It had been far too long since he had seen her like this. The last time he had seen Mabel’s chest her breasts were barely there, her areolas just dark circles and her nipples as small as the tip of his finger. Now, her breasts were just starting to grow, but they were already perky and adorable. Her nipples hardened from the gentle breeze blowing through the forest and the sight caused Dipper’s cock to throb. 

Mabel squirmed under her brother’s awe-struck gaze, clasping her hands behind her back to keep from covering herself. She looked up at her brother through her eyelashes. “What do you think?” she asked quietly, barely above a whisper. 

Dipper’s head was foggy and it felt like every one of his thoughts had to trudge through thick mud before he could actually process it. What did he think? He thought that Mabel was pure perfection, plain and simple. No one would ever be able to top her charm and beauty. Mabel’s bra slipped out of Dipper’s fingers where it was left to lay abandoned in the grass. Slowly, Dipper stepped towards his sister and his eyes trailed down to further gawk at her breasts. Mabel grew stock still as her brother admired her body. His unwavering gaze caused her heart to flutter and her clit to pulse rhythmically. At last, Dipper reached his hands forward and went to cup his sister’s breasts, gently kneading the soft mounds. Mabel sighed through her nostrils and leaned into her brother’s touch. Goosebumps appeared all over her frame. Dipper then squeezed her breasts with utmost care like he was afraid of breaking her, but Mabel would soon prove to him that she wasn’t to be treated delicately. 

Dipper brushed the pads of his thumbs over Mabel’s perky nipples, sending coursing tingles up her areolas and across her chest. Dipper continued to press and lightly pinch her buds until her breasts firmed up even more in his hands. Mabel let out a squeaky moan. “Ah! Dipper,” she mewled seductively before grabbing hold of both of Dipper’s wrists. She couldn’t take this soft play any longer. She had been waiting for this moment her entire life. She wanted to get down to  _ business _ . Dipper would have plenty of time to worship her breasts after he took her virginity. “Not now...Please, let’s just—Let me,” she mumbled as she pushed her brother’s hands away from her chest. 

With that, Mabel got down onto her knees before her brother, her half-lidded brown eyes sparkling in the morning sun. Dipper gulped and felt the heavy weight of his cock begin to stretch out the confines of his pants. He was harder than he had ever been before, even when he had been with Wendy, Pacifica, and Candy. Normally, it wasn’t difficult for him to get it up, but this had to have been a new record for himself; his dick seemed to want any and all attention it could get from Mabel, and he wasn’t about to complain about it. Mabel reached up to take hold of Dipper by his hips. She popped open the button of his shorts. Then, Dipper was captivated by the most erotic sight: Mabel leaning forward to grab his zipper in between her teeth, gradually unzipping him until his hefty package was freed. It filled out his boxers and bulged out in front of Mabel’s face. Dipper found it hard to breathe much less think, but he did know that all he wanted in that moment was for Mabel to touch him; he knew that no matter what Mabel did to him, it would bring him unbelievable amounts of pleasure. 

Mabel ignored Dipper’s apparent admiration of her in favor of tugging down his shorts to his ankles. Her hot breath ghosted over the tent in his boxers and she couldn’t help but smirk when her brother shuddered. Cooing, she reached out to rub his prominent erection, fondling it from head to sack. She cupped Dipper’s plump balls in the palm of her hand, lightly juggling them as she watched her brother’s reaction. His face scrunched up and he attempted to shimmy from side to side as he felt that pressure within his gut mount. His hands clenched and unclenched down at his sides. 

“Weren’t you the one telling me to hurry it up just a minute ago?” Dipper teased with a husky laugh. The ringing in his ears intensified for a moment, then it grew muffled once again. 

Mabel smacked her lips and settled onto her knees. “Right,” she muttered before going to yank Dipper’s boxers down to join his shorts. 

A lewd moan forced its way out of Mabel’s throat when her brother’s massive cock was finally revealed to her. It flopped out of his boxers, his uncircumcised head pulsing and fat sack distending. Mabel ogled her brother’s member in an attempt to commit to her memory just in case this would be the only chance she got to see it. Sure, Mabel had seen many of Dipper’s unwanted boners throughout the years, but the last time she recalled seeing it out in the open was when they were still little enough to bathe together. Dipper had certainly grown into his own since then as his long shaft tempted her. Just as Dipper had marveled at her breasts previously, Mabel appreciated every inch of her brother’s cock. Mabel slowly reached up to wrap her hand around the middle of Dipper’s dick, holding him with reverence typically reserved for sacred items. He watched her eyes continue to sparkle as she gingerly pulled his foreskin back to unveil his glistening pink head. 

A pearl of pre-cum bubbled its way to the surface of his tip, and Mabel’s hungry eyes were instantly locked onto it. Impassioned, she leaned forward to swipe her tongue across his head and finally got a real taste of her brother for herself. It was the tiniest bead of bittersweet seed and yet it set her mouth ablaze. She wanted  _ more _ . The ringing in Mabel’s ears increased in volume until it sounded like crackling static in her head. It commanded her to listen to her gut and without any warning whatsoever she opened her mouth and went to suckle at his mushroom head. 

Dipper wasn’t expecting his sister to just dive in like that. A guttural groan escaped him and his hands floundered for something to grab hold of until they found themselves tangled in Mabel’s thick brown locks. He grasped onto her scalp for dear life, worried that his lust would overtake him and cause him to violently begin thrusting into his sister’s mouth when she wasn’t ready. Dipper’s tight hold on Mabel only spurred her on as she moaned around his tip, quickly lavishing it in her saliva. Her tongue swirled around and around it, lapping up any of Dipper’s tangy sweat, and then she would lecherously suck on it, slurping down her own spit. The suction provided by Mabel’s mouth was just enough to ignite that spark of arousal within Dipper that made his cock grow even larger in Mabel’s hand and mouth. Mabel made a delightful noise in the back of her throat when she realized that her brother’s dick was pushing even farther into her mouth. She slithered her tongue underneath the head to flick at the underside of it while she established a pattern of hollowing out her cheeks around his tip and twisting his shaft. 

Dipper tossed his head back in approval as Mabel worked him up. His hips sputtered, desperately wanting to buck, but he restrained himself for her. Had he been with Wendy, Pacifica, or Candy in this moment, he wouldn’t have cared, but this was Mabel, his sister; she deserved every little ounce of tender loving care he could provide her with. Meanwhile Mabel’s throat was starting to itch from how badly she was craving Dipper’s cock. She didn’t care how Dipper treated her just as long as she got what she had so tirelessly desired over the years. Bracing Dipper for what she was about to do, her twisting of his shaft turned to fervid stroking. Each pump dragged Dipper’s foreskin back and she couldn’t wait to feel that moving inside her. She couldn’t wait to have Dipper inside her  _ period _ , which was why she felt it best to speed things along. 

Mabel whined around Dipper’s dick. She held his foreskin back with her hand wrapped tightly around the base of his shaft. Her gaze flickered up to watch the gentle bobbing of Dipper’s Adam’s apple as she began to take him further into her mouth. Mabel took her time moving up Dipper’s shaft. She was fully aware of her own gag reflex, but she wanted to impress Dipper and not choke halfway down his cock. Her mouth was as wide as she could make it when she started moving up his length. A rush of saliva filled her mouth along with Dipper’s erection. Some of it oozed out of the corner of her mouth and dribbled down to her chin. Her free hand had her own knee in a vice-like grip to keep from touching herself. Right now, she was completely focused on Dipper’s pleasure and not her own despite how slick her thighs were becoming. Mabel went to rub her thighs together to sate her growing need only for a faint squelching to meet her ears. Heat blossomed to her cheeks, though Dipper failed to register the sound as he was too busy relishing in the feeling of Mabel’s warm mouth around his cock. 

Since Dipper didn’t seem to mind Mabel’s obscene noises, she continued to shimmy her moist thighs together as she finally managed to take in half of Dipper’s massive erection. His tip nudged at the back of her throat, agitating her gag reflex, but Mabel was persistent. While she waited for her body to adjust to Dipper’s girth, she stroked what remained, expertly twisting her wrist at just the right moments. Her ministrations were so divine that they elicited a deep moan from Dipper. He accidentally on Mabel’s hair, which pulled at her scalp and delivered a pleasing shock throughout her frame. Her eyes slipped shut in bliss and subconsciously her jaw relaxed to the point where she could take even more of her brother into her mouth. Slowly but surely, Dipper’s huge dick took the plunge down Mabel’s throat. He fit snugly down inside his sister, her muscles tightening around him, rubbing him in all the right spots. The small flame in Dipper’s stomach burned even brighter. Without thinking, he snapped his hips forward and fully sheathed himself down Mabel’s windpipe. Mabel’s tiny yelp was muffled as Dipper held her head close to him, burying her nose in his dark pubes. His balls smacked against her drooly chin. 

Mabel winced and prepared herself to deal with the gagging that was sure to come, but to her utter surprise, her gag reflex didn’t act up. Instead, she was free to breathe through her nostrils and hold Dipper’s cock securely down her esophagus. Both of her hands came up to grasp onto the outsides of Dipper’s thighs to keep herself steady as she was certain that Dipper was about to lose all of his inhibitions. She couldn’t wait any longer for her brother to use her to his heart’s content; it’s what sisters were for. Rivulets of Mabel’s lubricant trickled down her thighs. Her body was more than ready to take on whatever Dipper had in store for her. To prove it to him, Mabel forced her own throat to constrict around Dipper before swallowing harshly. She felt their heart beats sync, a silent moment of pause, and then Dipper unleashed the savage beast that she knew he had been hiding.

With a vicious growl, Dipper pulled himself out of Mabel’s throat and left only his tip inside her mouth. Mabel’s nails dug into his bare skin as she braced for her brother’s onslaught. She kept her esophagus as relaxed as she could and internally sighed in relief when his cock once more took refuge down her throat without any hold-ups. She was immensely proud of herself for keeping her gag reflex at bay because she knew Dipper was thoroughly going to enjoy being deep-throated by his sister. After that initial thrust, Dipper was quick to set a violent pace. His crotch collided with Mabel’s face with every buck of his hips, his balls swinging wildly against her chin like an angry bull’s. The ringing in Dipper’s ears and the raging inferno in his belly fueled him and made it impossible for him to resist fucking his sister as hard as he could. He had waited too long for this opportunity and he wasn’t about to ruin it by being mediocre for Mabel. All reservations had been abandoned. He wanted each thrust to get his tip closer and closer to breaching into Mabel’s stomach. 

Mabel moaned sweetly around Dipper’s cock, the vibrations causing his length to throb and twitch within his sister’s throat. Mabel stayed complacent as Dipper face fucked her, savoring every movement he made and every little grunt or groan that tumbled past his lips. If only Dipper hadn’t been denying his true feelings, they could have had this so much sooner. But, it was here now and she was striving to make it the single best sexual experience of Dipper’s young life. Hesitantly, Mabel released her grip on Dipper’s thigh with one hand in order to bring it forward to fondle his taut sack. She kneaded his balls as he erratically thrusted into her, loving the sensation of the bulbous wrinkly flesh on her fingers. 

“F-Fuck, Mabel!” Dipper cried out among the filthy smacking of his groin and his sister’s face. 

Even with her full mouth, Mabel was still able to curl her lips, delighted that she could please her brother in this way. Soon enough, a steady stream of gargles emitted from Mabel. While she couldn’t do much in her current position, she still wanted to help Dipper achieve his orgasm in any way she could. She was rewarded for her actions by an increase in Dipper’s pace that had her already hazy head spinning. At this rate, Dipper was going to rub her throat raw, but Mabel would proudly talk with a hoarse voice for the rest of the week if it meant satisfying her brother. Dipper gritted his teeth as he felt himself approaching his climax. That heat in the pit of his stomach was beginning to coil, and he was craving more and more of that delicious friction that Mabel’s esophagus was providing him. He managed to kick his thrusting into overdrive, and every time he pulled himself from Mabel’s depths she would gurgle cutely, happily welcoming his cock back inside. He wanted to show his sister just how much she meant to him by coming deep down her throat. 

Mabel had moved on from just massaging his balls to squeezing and pinching them. Each press of Mabel’s hand to his sack made his dick pulse like he was about to come from that alone. He held out though for Mabel’s sake, staring straight ahead at the lush forest to distract his mind from the insane amount of ecstasy that he was experiencing. Mabel could tell from how sloppy Dipper’s thrusts had become that he was close, and she whined and whimpered around his cock, pleading for his thick gooey cum to fill her from the inside out; she had been craving his load from day one and she was ready to make her dream a reality. She suddenly clutched tightly at Dipper’s balls, tugging them down with the movement, and Dipper growled at the abrupt rush of pleasure tickling his spine. He slammed back down Mabel’s throat one final time before shooting a mighty load of creamy cum down into her belly. 

Humming contently, Mabel eagerly suckled on Dipper’s cock to milk him of everything he had; she didn’t want to miss out on a single drop of her brother’s seed. She massaged his sack in her hand languidly to get him through the high of his climax while swallowing down the rest of his delectable jizz. She rubbed her thighs together to quell her own rising arousal. Her swollen clit was mashed in between her damp folds and desperate for some attention of its own, but she knew it would receive it all in due time; there was no way her own brother was going to leave her hanging. 

After Mabel had dutifully swallowed down all of Dipper’s cum like a good older sister (by five minutes), she fully expected him to pull out and pin her to the ground so he could ravage her aching pussy, but instead he remained still inside her throat. Gently, she tilted her head up and rose a brow at him only to find Dipper with his eyes shut in what appeared to be deep concentration. She assumed that her brother was still reeling from his orgasm or that he simply enjoyed using her as a cock sleeve. Whatever the case may be, she was happy to indulge him as long as he got to fucking her eventually. If too much time passed, then she would absolutely coerce him into pulling out. 

But, what Mabel failed to realize was that Dipper had another far hotter load planned for his sister. Once Dipper had came, he recognized that familiar pressure mounting in his bladder. He didn’t know he had had to piss so badly, but now he was dying to let go, and he figured that his sister wouldn’t mind the chance to swallow down his urine as well. He hissed when he felt that pressure gradually start to subside and give way. A warmth tickled through his crotch, and his grip on Mabel’s hair grew that much tighter. Mabel had no idea what was happening until it was too late and her brother was pissing down her already thoroughly abused windpipe. Her eyes widened to the size of saucers when she felt that hot liquid scorch her muscles and cascade down into her already cum-filled belly. Dipper watched with immense satisfaction as a bright red blush spread across Mabel’s face; he knew his sister wouldn’t mind this in the slightest. 

A sheepish whine bubbled up in Mabel’s stuffed throat, and her pussy throbbed at the sensation of drinking down her brother’s piss. Certainly, she had not expected it, but if that’s what Dipper wanted out of her, then so be it. If anyone was going to get her to be a human toilet, it would be her loving twin. Eventually, her esophagus grew accustomed to the warmth of Dipper’s pee and she hesitantly swallowed it down just as she had with his cum. Once Dipper’s stream died off to a gentle flow, Mabel felt bloated. Dipper’s cum  _ and  _ piss were now sloshing around inside her stomach, her brother’s perfect gift for her. 

At last, Dipper dislodged himself from her throat. He shook out the last droplets of his piss onto Mabel’s face. She wiggled some feeling back into her jaw and giggled. Dipper thought she looked radiant on her knees before him, smiling and blushing, and with a belly full of his fluids. 

But, Dipper was nowhere near finished with his sister. The ringing in his ears had turned deafening and it seemed like the only way to appease it was by having his way with Mabel. 

“My turn for a taste, sis. Lie down on your back,” Dipper commanded and that rosy color extended down to Mabel’s supple breasts. However, she was quick to comply with his demands and enthusiastically spread her legs once she was laying down in the grass. She teased her brother for a moment by timidly running her hands over her panties and the puffy mound concealed underneath them, but now wasn’t the time for games. Hurriedly, she pulled them down her legs and flung them off to the side. Dipper got down onto all fours and crawled his way over to her, his eyes wide as he took in the sight of his sister’s pretty pink pussy. 

The last time he had seen Mabel’s vagina was when he hadn’t even known what is was. It had been completely bare and smooth, and a younger Dipper had been confused as to why his sister had nothing on her crotch when he clearly had a large cock there. Now, Mabel’s crotch was covered in a layer of curly dark pubes and sopping wet. He could see her pussy glistening with lubricant in the sunlight; she was  _ more  _ than ready for him, but he still wanted a taste for himself seeing as Mabel had gotten more than her fair share of him. Ignoring his urge to admire her for now, Dipper clamoured up on top of Mabel so that his head was between her legs and his reawakening dick was hovering above Mabel’s face. They were in the perfect position for tasting each other, and he couldn’t wait a second longer. 

He reached down with both hands and cursed under his breath when he noticed they were trembling. Taking in a deep breath, Dipper steeled himself and brushed the pads of his fingers over Mabel’s lips. At the faintest touch, Mabel’s hips jerked and some of her lubricant sprayed up onto Dipper’s face. He greedily licked up the few droplets on his face, hungry for more. He spread Mabel’s lips with his fingers and watched her little clit throb frantically. Mabel was so caught up in what Dipper was about to do to her that she almost forgot to do the same for him. She leaned up to place a tiny peck to his tip, letting him know that she was ready. She opened her mouth and allowed him to slide back down her throat, more than willing to serve as her brother’s cock sleeve while he ate her out. Once his balls were resting on the bridge of Mabel’s nose, Dipper leaned down himself to see exactly what his sister tasted like. 

Tentatively, Dipper stuck his tongue out and maneuvered his face closer to his sister’s hot moist pussy. He felt her heat radiate against his own cheeks before he was upon her, experimentally swirling the tip of his tongue about her hardened nub. Mabel mewled around his cock and squirmed underneath Dipper as her wildest dreams had finally been realized. Dipper hummed in the back of his throat at the subtle tang of Mabel on his tongue. He lapped at her pulsating clit that beat in time with her heart. He couldn’t get enough of the little bud. Mabel’s toes instinctively curled into the grass while her hands searched for something to grasp too. She ended up reaching up for Dipper’s hips again, encouraging him to sink even farther down her esophagus. Mabel’s clit was like a piece of lemon candy to him, so he couldn’t stop himself from enclosing his mouth over it and giving it a firm suck. Mabel squealed around Dipper’s dick, which caused him to thrust lightly down into her. He suckled on her clit for a moment, then grazed it with his teeth when he went to pop off of it. After Dipper’s treatment, Mabel’s clit was inflamed and bulging, though he decided it was time to move on. 

Dipper trailed lower down, following the curves of Mabel’s pussy. His lips brushed her thin folds, and he poked his tongue out just to teasingly swipe at her urethra. Dipper felt her shudder against him, and he smirked wolfishly. Mabel fruitlessly mouthed at Dipper’s steadily stiffening cock and wondered if she would be rewarded with another splash of cum for appeasing Dipper’s taste buds. Dipper went to lick a straight line down the entirety Mabel’s pussy, but found that he couldn’t quite reach her leaking hole. His hands managed to worm their way underneath her hips to pull her lower half closer. Instantly, his nose was buried in her dripping wet folds, and the stark scent of citrus assaulted his nostrils. Just as his tongue went to delve deeper into his sister, Mabel jerked from overstimulation and Dipper lost his balance thanks to their contorted position. He gripped her hips tightly as he fell over, taking Mabel with him. They both ended up on their sides in the grass with Dipper’s huge dick still stuck in Mabel’s throat and Dipper’s face that much closer to Mabel’s quivering hole. 

Akin to a mad man, Dipper wasted no time in diving in. He didn’t even give his sister a chance to lift her leg to allow him more room; he was too far gone to wait at this point. Mabel choked around Dipper’s cock for the first time and not because of her gag reflex. Dipper’s tongue had started to trace the outside rim of her pliable entrance and then he gingerly sunk the tip of it within her. Mabel’s eyes squeezed shut as giant waves of pleasure crashed over her quaking frame. She attempted to bob her head on Dipper’s cock in order to stimulate him as much as he was stimulating her, but it was futile; Dipper’s tongue felt far too good in her pussy, warm and wriggling. It tickled something deep within her, igniting a pressure that she hadn’t noticed until Dipper began tasting her insides. She writhed and concentrated on holding up her leg for him as she didn’t want him to stop any time soon. 

Mabel tasted like a cool ice cream on a blistering summer day. Her essence was light and sticky on his tongue. It consisted of an addictive flavor that Dipper couldn’t get enough of. Every time he lapped up a drop his tongue demanded ten more. He was like a pig digging through a trough for the truffles under all the rot: sloppy and desperate. His chin was covered in Mabel’s lubricant and droplets sprayed against his cheeks from all her wiggling. He tried ramming his tongue in deeper to lap at her contracting walls, but his tongue wasn’t long enough. Frustrated, his own hips began to uselessly buck against Mabel’s face, once again rubbing her already raw windpipe. Although, Mabel seemed to be on another plane of existence entirely due to Dipper’s sinuous tongue. The only thing that would feel better in her pussy would be his thick cock and she knew that was soon to come. 

Yet, there was something else tugging at her, a familiar feeling settling in her own bladder. Once Dipper’s tongue had slithered its way inside her, it became apparent that she had to  _ go _ , but she had been trying her best to hold it in at least until Dipper had had his fill of her. In the back of her mind, she knew that Dipper wouldn’t mind having a taste of her piss as well, especially considering he had done the same to her earlier. Despite that, Dipper was so close to her urethra that she feared he would be upset if she suddenly started gushing piss all over him. Her meek bobbing grew more furious as she tried to get Dipper off quicker, so she could use the bathroom without any consequences. Mabel’s plan backfired on her, however, as Dipper was reinvigorated by her ministrations. His tongue flicked upwards inside her, caressing the top of her canal and irritating the floor of her bladder. She abruptly felt the tension in her lower stomach give way, but she couldn’t even warn Dipper about her pee with his hung member clogging her throat. 

Dipper registered Mabel’s muffled scream from the way it tingled his already overstimulated cock. For a moment, he believed he had hit a sweet spot inside her. He continued laving over the roof of Mabel’s passage, which only worsened her predicament. A faint hiss filled Dipper’s ears and then there was something inexplicably warm splashing against his face. It rained down over one of his cheeks and his chin before winding its way down his neck. Dipper’s eyes snapped open as he tried to figure out what was happening, though he didn’t falter in his tongue thrusting as Mabel’s walls flexed around his wet appendage. However, after listening intently to the strange trickling sound, he realized that his sister was pissing on him, and there was no way in hell that he was going to miss out on his chance to taste that too. 

He made circles with his tongue while gradually inching himself out of Mabel’s hole. When he at last popped free he kept his mouth wide open in order to catch what was left of Mabel’s stream. His sister whined at the loss of his curious tongue within her heat, though she had a feeling as to why her pussy was now empty even if she couldn’t see Dipper; the subtle splashing of her piss inside Dipper’s mouth gave it away. Dipper waited until his mouth was filled to the brim with Mabel’s urine before swallowing it down in one large gulp. Her pee warmed his throat as it traveled down into his belly. He was a little disappointed that her piss didn’t have a distinct taste. It was akin to lukewarm water, but that didn’t matter to him. It was his sister’s piss and that made it special to him all the same. 

It was too bad that all good things eventually come to an end because he would have gladly guzzled down Mabel’s piss for hours. Her gushing waterfall of piss soon morphed into a gentle spray. Reluctant to believe Mabel was finished urinating, Dipper pressed his face even closer to her pussy and enveloped her clitoral hood into his mouth to catch every last drop. Mabel shamelessly rutted against her brother’s face, and her throat clamped down onto Dipper’s dick at that exact moment. Dipper rolled his own hips against his sister’s face as he felt his gut simmer with need. Once Mabel’s stream completely vanished, Dipper suckled on her engorged clit while coming a second time down Mabel’s esophagus. This time Mabel was expecting her brother’s cum to shoot into her, so she reveled in its glory, letting it fill her already stuffed stomach. Dipper really knew how to treat a girl, and yet he still hadn’t even fucked her. 

Dipper proceeded to mouth at his sister’s clitoral hood while basking in the final throes of his second orgasm. Most guys wouldn’t be able to keep it up any longer, but Dipper had built up plenty of stamina by fucking his little harem continuously. When he did pull himself out of Mabel’s mouth his cock was beginning to stiffen again, ready for the main event. Mabel’s mouth was gaping from having to accommodate such a monstrous member. She was panting profusely in an attempt to fill her burning lungs with much needed fresh air. While Dipper waited for his sister to recover from that round he furiously jerked himself back to life, pumping until his tip was red and inflamed. 

Abruptly, the giant stone behind them shook, and the ground underneath them rumbled. The stone emitted another high-pitched frequency towards them, which assaulted their ears and continued to fill their heads with impure thoughts. The buzzing was screaming at them that it was finally time to consummate their relationship. There was no time left for foreplay. Even though Mabel had felt spent moments ago she forced herself to flip onto her bloated belly. She lifted herself up onto all fours before her brother, spreading her legs as far apart as she could to put her dripping wet pussy and round ass out on full display. Dipper groaned and gave into the frequency’s urgings as well. He scooted over to his sister on his knees, gripping his now rock hard cock in his hand. He reached his free hand out to grab Mabel’s left cheek, running the pad of his thumb across the soft skin, and pulled it back to allow himself easier access to her pussy. Satisfied with the twins’ actions, the earth stopped quaking and the frequency died down. The ringing in their ears grew muted, but they didn’t need it to command them to fuck. 

“I’m ready for you, Dipper,” Mabel moaned while grinding her ass back against him. “I’ve been ready for this moment since I was born.” 

Dipper chuckled as he went to press the tip of his cock to Mabel’s slick labia. “I know, sis. You were born for  _ this _ ,” he emphasized before pushing his mushroom head into her. 

Mabel’s thoroughly wet and stretched entrance easily submitted to Dipper’s girth. His fat head popped right into her pussy, and to Dipper it felt like coming home. He moved his hand back to the base of his cock, still guiding it through. Mabel’s sore jaw slackened to allow her tongue to flop out. Her eyes rolled into the back of her head as she was overcome with bliss at finally being deflowered by her brother. She had scared off plenty of bachelors in the past because she knew that her virginity had been reserved for Dipper; if he couldn’t take it, then no one could. Despite never being dicked down, her brother had worked her up to the point that her pussy showed no restraint against his length. Her muscles remained complaisant and malleable while Dipper sunk into her. All Mabel had to do was sit back and relax. She was soaking in her brother’s attention and everything he had to offer her. She knew there was a possibility of her becoming pregnant if Dipper came inside her, but that was a small price to pay for being claimed. Besides, the thought of carrying her brother’s child made Mabel so unbelievably giddy that she released a noisy mewl and slammed her ass back against Dipper, fully sheathing him inside in one go. 

Dipper choked on a moan and quickly moved his hand out of the way as his balls tapped against Mabel’s ass. He blinked a few times to process what had just happened, but once he realized what Mabel had done, he laughed and gave one of her cheeks a hearty swat. Mabel yelped and rolled against Dipper, eager for him to begin plowing her into the ground. “Good girl,” he rumbled. He was about to grab onto Mabel’s hips for leverage while he pounded her little pussy when he spotted something even better. Smirking, he grabbed fistfuls of Mabel’s thick long locks and yanked her head back towards him. She whimpered sheepishly as her neck was arched and she was forced to keep her head up off the ground. 

“Dipper,  _ please _ ,” she whined and that was all it took for Dipper to start easing out of her. 

Mabel let out an inaudible gasp as Dipper’s cock dragged against her walls. She could feel his foreskin bunching up within her, which further nourished her stagnant arousal. He pulled out until only his tip remained inside and exerted pressure onto the rim of her leaking hole. Dipper clenched his fists around Mabel’s hair, then advanced forward. Mabel’s pussy squelched when it welcomed Dipper back inside again. His sister’s whole frame jerked with the power of his thrust. He felt his own back muscles flex, and he huffed like a feral beast through his nostrils. He was enveloped in Mabel’s moist cavern, and Dipper was sure this was what heaven felt like. He knew the in’s and out’s of his other girlfriends’ canals like the back of his own hand, but Mabel was uncharted territory that he had to explore and discover along the way. Normally, he would hit his other girlfriends’ G-spots on the first try, yet Mabel’s eluded him. He refused to start his usual speed-of-light fucking until he managed to find that little bundle of nerves; he wanted something he could ram his tip into every time and know that it was driving his sister crazy. 

Dipper rolled his hips and his cock widened Mabel’s walls in its search. He began shallowly thrusting at various angles, and Mabel bit down on her bottom lip as each buck of Dipper’s hips made her vision grow dark around the edges. She knew exactly what her brother was looking for, so she tried to help him out by rubbing her ass against his rotating hips. Dipper focused with all his might, the throbbing of his dick eating at his core, and almost went to give up on finding Mabel’s G-spot when out of exasperation he drove himself an inch deeper. Mabel’s bumpy inner walls guided his head upwards, and he smacked right into the center of her sweet spot. A predatory gleam appeared in Dipper’s eyes while Mabel obscenely keened at the sensation. White hot pleasure sparked up her back and lodged itself in the back of her skull, electrifying her brain to mush, and leaving only one thought unscathed: Dipper. Her brother didn’t disappoint as he took Mabel’s cry as his cue to start madly pistoning in and out of her damp passage. 

An incoherent slew of noises burst forth from Mabel’s mouth as soon as her brother ramped up his speed. It felt good to have him settled inside her, but it felt even better to be at his mercy and receive the pounding of her life. All that searching certainly paid off because Dipper was able to strike her G-spot with every thrust. After the first hit, she felt woozy. After the third hit, her G-spot started to burn. After the fifth hit, she couldn’t even register the pain anymore, the pleasure drowning everything else out. Dipper subconsciously kept yanking her hair back even farther, tugging at her scalp and delighting yet another part of her. Dipper was a maniac in bed, and Mabel was eternally grateful that she was getting to experience him in all his glory. Her brother was fucking her so hard that she swore she could hear his fluids sloshing around in her belly. Her labia quivered with every lunge of Dipper’s cock, once more trapping her sensitive and pulsating clit. Mabel’s heart beat in time with Dipper’s pounding to the point that her rose-colored chest was heaving. 

Dipper had completely lost himself to the contractions of his sister’s pussy. He wanted more of everything that Mabel could give him. In Dipper’s mind, Mabel existed on an entirely different plane than his other girlfriends. Mabel was angelic in every sense of the word and the way her pussy greedily sucked him back in after each shove of his hips only proved that. Sweat collected along Dipper’s brow and glimmered across his chest, yet his stamina prevailed. Again, Dipper wasn’t about to disrespect his beautiful twin sister by coming at his usual rate; he would hold out for her sake. He did, however, change his thrusting so that he was no longer pulling all the way out of Mabel for every slam. He fucked her deeply, stirring up her insides and her full belly. He wanted to come inside his sister’s pussy no matter the risk. In fact, the ringing in his ears was adamant about shooting his load into Mabel, filling his mind with thoughts surrounding her with a swollen belly as she carried his child. That thought sparked something primal deep within Dipper, an instinct long forgotten, and suddenly he was drilling into Mabel’s G-spot like there was no tomorrow. 

Mabel let loose a strained howl of pleasure. That little bundle of nerves within her was being jabbed and mashed so fiercely that her legs began to jiggle underneath her. She desperately wished to fall to the ground, so that some of that pressure would be assuaged and Dipper could continue to ravish her to his heart’s content, but since her brother had her hair in a vice-grip, she was unable to. Forced to remain upright and endure Dipper’s beating to her G-spot, Mabel came violently around his cock. Her pussy made a loud queefing sound and squirted lubricant all over Dipper’s thighs. Her walls tightened beyond belief around Dipper, attempting to restrain his movement for the first time, but he persisted and continued to press forward until he collided with Mabel’s cervix. Mabel choked on a delirious sob while her clit pounded away from the best climax it had ever experienced. Dipper held out until Mabel’s walls started undulating around him, practically beating his hard cock into submission. He impaled her pussy one last time, ramming his head right into her cervix before releasing his massive load into her womb. Ropes of thick cum spilled into Mabel. Dipper’s seed was so deep inside her that she felt like it too was joining his earlier loads in her stomach. 

For a brief moment, the ringing in their ears intensified until it blocked out all other noise. Unbeknownst to the twins, the ancient power of the rock they had stumbled upon guaranteed that Dipper’s seed would fertilize one of Mabel’s eggs. Dipper had unintentionally just impregnated his sister, though once the duo would come to find out the consequence of their love-making, they would be overcome with immense joy at having a baby of their own. As soon as Mabel’s egg was fertilized, the ringing in their ears vanished without a trace and the stone gingerly settled. 

Dipper’s grip on Mabel’s hair slackened and she was at last able to press her chest to the ground. She grinded back into Dipper’s crotch to ride out the final waves of her orgasm, fully prepared to pass out here naked in the field after that pounding, but Dipper still wasn’t finished with her. Even though the ringing had dissipated, Dipper had gotten a taste of his sister and his thirst had yet to be quenched. He pried himself out of Mabel’s fucked pussy and without so much as batting an eye he lined his tip up with Mabel’s other more wrinkled hole. Mabel’s heart stilled in her chest and her tired eyes widened when she realized what Dipper was doing. The beast within her brother truly had been awakened, and there was nothing she could do to stop him  _ even if she wanted to _ . With lightning-quick reflexes, Mabel flexed her sphincter to facilitate Dipper’s entry into her ass. He pushed his uncircumcised head into Mabel’s dry orifice, and her muscles pulled up his foreskin as he entered. Mabel rubbed her cheek into the ground at the sensation of Dipper’s hefty package filling her ass. She had never considered anal before, but she was Dipper’s now, which meant he could do whatever he wanted to with her. 

It was much more difficult for Dipper to squeeze into Mabel’s ass since there was no lubricant to help him. Urgently, he bucked his hips to inch deeper and deeper into her second passage. Mabel felt the weight of Dipper’s massive cock dig into her pussy and her legs spread to their limit under the pressure. Dipper’s hands found leverage on Mabel’s hips, his grasp so hard that it was sure to leave bruises. He pulled Mabel up against him while continuing to snap his own hips until he had sunk into his sister’s ass. Her muscles were already clamping down around him, but he was determined to have his fill of his twin before he succumbed to yet another climax. Dipper grit his teeth and started to move. The easy part of plowing Mabel’s ass was pulling out, though once he drove himself back inside, he felt stuck. But after a few slow full thrusts, Mabel’s ass adjusted to his girth and allowed him to fuck it just as viciously as he had her pussy. Mabel was so exhausted that all she could do was keen affectionately while her brother repeatedly rammed her ass. Eventually, Dipper figured out that it was easier to shallowly fuck Mabel instead of pulling all the way out each time. His dick pummeled her seemingly endless canal. There was no G-spot or cervix for him to collide with here, and thus, he was free to charge in at full speed. 

Mabel’s frame rocked in time with Dipper’s thrusts. Her head was way up in the clouds, the euphoria she received from Dipper’s first fucking too great for her to handle. She was lost in a perpetual stupor and had Dipper been able to see her face in this moment he would have sworn that Mabel’s pupils had turned into little hearts only for him. Dipper squeezed his eyes shut as he felt that heat coil in his gut again, the inferno swirling in his stomach reaching its peak. He knew that this would be his last round, and he wanted to savor it. He pressed himself against Mabel’s back, burying his face into her hair that smelled like her coconut shampoo. He plowed and plowed into her ass, riding that colossal wave of pleasure until it towered over his head and came crashing down over him. Dipper’s hot cum suddenly spilled inside Mabel’s ass, and she felt far too full. Her muscles contracted around Dipper in surprise and coaxed the last droplets of cream right out of him. That last wave of pleasure had extinguished the inferno within him, leaving Dipper totally sated and sleepy. He was perfectly content to stay melded to his sister in the field and revel in their afterglows together, yet something in the back of his mind persuaded him to do otherwise. 

He managed to pull himself up and then out of Mabel, whistling lowly when he saw the damage he had done to his sister. He had completely wrecked her. Both of her holes were red and gaping, uselessly twitching now that they were empty. He felt a bit bad for going all out on her for their first time, so he reached out to tenderly knead the cheek he had slapped earlier, rubbing soothing circles into her backside. Mabel hummed in contentment, and her eyes threatened to flutter shut. There was still a small amount of pressure in her gut; however, she was quick to remedy the situation with a little push. A wolfish smirk spread across Dipper’s lips when he saw Mabel’s pussy spasm. All at once, his huge creampie dribbled out of her stretched hole. He watched his cum coat her labia and cascade over her abused clit before it landed with a plop on the ground below. Yet, his attention turned back to her ass when it crackled. Mabel’s hole puckered and strained as his other creampie bubbled out of her to join the mess he had made of her pussy. 

Dipper’s hand trailed down to rub the pad of his thumb between Mabel’s lips, her skin pliable and dirty, to spread his own cum. “I’ve made such a mess out of you, huh?” he teasingly whispered, and Mabel sighed softly in reply. 

He indulged in Mabel’s destroyed pussy for a moment longer, then stood. He stretched his arms up above his head, and he turned on his heel to face the stone. Dipper still wasn’t sure what if anything the stone did. While it had felt like something else had been nudging at him to take Mabel immediately, that wasn’t exactly a bad thing. In fact, if the stone had made them fuck, then he was grateful for stumbling upon its entry in the journal. Speaking of which, he eyed the book that he had tossed aside when his skin burned to touch his sister. He slowly approached it, body still reeling from the pounding he had given Mabel. The journal was wide open, and Dipper noticed that it was still flipped to the page with the weird rock on it. But...There was something different about the page. 

Dipper bent down to examine it and couldn't believe his own eyes! Before the page had only said “STAY AWAY!!!” and now the writing had changed completely. In place of the warning was the actual description of the rock. 

**_THE STONE OF INCEST_ **

**_Do not approach under any circumstances. This stone is able to permanently bond two family members together and awaken more than a familial love between them even if these feelings were not present before interacting with the stone._ **

Dipper read the new description three times before his addled mind was finally able to properly interpret it. The new entry explained why the twins had suddenly grown feverish with lust for one another. And while a part of Dipper felt violated, he mostly felt thankful. He and Mabel had been chasing around the bush for so long, unable to admit their true feelings to one another or make the first move. Had they not stumbled across the stone today, they would still be entirely distant from one another and equally dissatisfied with their lives. The stone had forced them to act on their feelings and to put everything out in the open between the two of them. Now, Dipper had taken his sister’s virginity and no doubt gotten her pregnant if the stone was that powerful. His heart was filled with love, his previously insatiable lust had been quenched, and he would be a father soon. If anything, the stone had changed their lives for the better. Mabel was his forevermore…

_ Clink! _

“Huh?” Dipper blinked and straightened, trying to identify the source of the noise. He looked back down at the journal to find a small gray ring laying next to it. The ring seemed to be calling out to him, demanding that he pick it up. He obeyed. The ring was made entirely out of stone and chilled the tips of his fingers. He inspected it, but there was no engraving on it. An eerie gust of wind blew through his hair, causing him to look up and face the magnificent stone in front of him. Dipper stared it down, asking it whether or not this meant what he thought it did. Would he really be able to permanently bond Mabel to him with this ring? There was a resounding buzzing in his ears, and Dipper regarded that as a reassuring  _ yes _ . 

“Dipper?”

He whirled around to face his sister, who had felt compelled to get up as well despite how all of her limbs felt like jelly. Dipper’s cum was still oozing down her thighs and backside. He smiled tenderly at his twin. 

“Mabel, there’s something I need to ask you,” he said quietly, then fell to one knee. Mabel’s eyes widened at her brother’s pose; however, when he beckoned for her right hand she held it out for him nonetheless. “Mabel Pines...Will you marry me and stay with me until death do us part?” He revealed the stone ring to her, waiting for her answer before he slipped it onto her finger. 

A pregnant pause fell over the twins. Mabel stared at her brother in astonishment. Was this really happening? It felt like a dream. Mabel’s very irises shook as a brilliant grin spread across her face. Her answer was ripe on the tip of her tongue until she remembered...

“What about the others?” she asked. 

“Say the word and I’ll never speak to any of them again,” Dipper reassured her, his words genuine and from the heart. 

“No, keep them...I don’t mind sharing you,” Mabel confessed with a light blush, and Dipper knew she was the one for him. 

Mabel paused again before she squealed and hopped from foot to foot, rapidly nodding her head. “But, of course, I’ll marry you, Dipper! You know that would make me the happiest girl in the world!”

Dipper’s own eyes grew soft, his expression conveying nothing but true love for Mabel, and he gently slipped the stone ring onto her finger; it fit perfectly. The stone behind them seemed to groan in satisfaction, but Dipper didn’t have time to think about it too much as Mabel enveloped him in a tight hug, her arms wrapping around his neck. 

“You’re the best brother ever!” 

Sometimes even mysteries have happily ever after’s. 

**Author's Note:**

> Thank you for reading and I hope you enjoyed it! That was simply a small taste of Madam Kuro's talents and I hope to grant even more obscene wishes in the future.
> 
> What can Madam Kuro do for you? My purpose is to bring others' kinkest fantasies to life. There is little I won't do, so step forward and let Madam Kuro know your deepest and darkest desires. What is your most self-indulgent wish? The works I have posted here are all wishes from others that I have granted. Yours could be next. All you have to do is send Madam Kuro an email at madamkuroshi@gmail.com to make your fantasies a reality. Through email, I will provide you with my rules, so you can decide for yourself if you really want Madam Kuro to grant your wish. You won't be disappointed.
> 
> Keep wishing~ <3


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